Adjustable overhead lift truck guard



Nov. 29, 1960 c. H. MOLITOR ETAL 2,962,179

ADJUSTABLE OVERHEAD LIFT TRUCK GUARD Filed Aug. 11, 1958 2 Sheets-Sheet 1 /9. 2/ cHAnLz rfxii f l gon Z BY ROBERT ATTORNEY Nov. 29, 1960 c. H. MOLITOR ETAL 2,962,179

' ADJUSTABLE OVERHEAD LIFT TRUCK GUARD Filed Aug. 11, 1958 2 Sheets-Sheet 2 50 7 64 i 5 1 0w 1 i N L46 1 P 7 I 58- 14 F 14. (,HARLE lt biia fioR ROBERT W. WOLFE a M- ATTORNEY Elite atent lice Ringoes, N.J., assignors to Union'Carbide Corporation, a corporation of New York Filed Aug. 11, 1958, Ser. No. 754,478

Claims. c1. 214-670) This invention relates to a safety device for industrial lift trucks and more particularly to an adjustable overhead guard therefor.

Materials handled by these trucks are frequently stacked or lifted to a height above the operator of the truck, and consequently overhead guards are provided on the trucks in order to prevent injury to the operator from accidental falling of the materials. It is often necessary for lift trucks to enter and pass through doorways of railroad cars, trucks, warehouses and the like, lacking clearance for safe passage of the lift truck because of the projecting height of the guard. Accordingly removal of the guard is necessary in order to gain entrance. Consequently, the lift truck operator has no protection against falling materials when operating the truck with the guard removed and ofter replacement of the guard is forgotten until an injury has occurred. it is, therefore, desirable to have a safety guard which does not have to be removed from the lift truck in order to pass through openings of restricted vertical clearance.

An object of this invention is to provide an adjustable 12, a steering mechanism 14, wheels 16 and a liftingdes vice 17.

The guard assembly 18 comprises a pair of L shaped tubular metal members 19, 19 having vertical leg sections 22, 22' and horizontal leg sections 21, 21. Metal cross members 20 are bolted, welded or otherwise secured to the horizontal leg sections 21, 21 at spaced intervals suflioiently close to bar passage therebetween of falling materials. The horizontal legsections 21, 21 are extended over and beyond the lift truck seat 12. The vertical leg sections 22, 22 are positioned in front of the operators seat 12. Mounting plates 26, 26 are attached to each vertical leg 22, 22'. Attached to each mounting plate 26, 26' are sleeve bearings 28, 28'. Vertical shafts 30, 30 are affixed to and are parallel and spaced apart from the vertical mast members 32, 32' forward'of the overhead safety guard for use with industrial lift truck's.

Another object of this invention is to provide a vertically adjustable overhead safety guard for use with industrial lift trucks.

Still another object of this invention is to provide in a lift truck an overhead guard which can be vertically adjusted to pass through areas of comparatively low overhead clearance and yet provide protection to the operator.

Another object is to provide an overhead safety guard, for use on industrial lift trucks, extending over and beyond the operators section and which is slidably mounted on shafts connected to the lift truck mast.

Another object is to provide a guard which is vertically adjustable, independently of the trucks lifting device or the tilted position of the mast of said lifting device.

Further objects and advantages will become apparent from this specification and appended claims.

The nature of the invention will be more clearly understood by reference to the following detailed description and in connection with accompanying drawings, wherein;

Fig. 1 is a schematic side view representation of an industrial lift truck with a hydraulically operated, vertically movable guard shown in its lowest position by solid lines, and in an elevated position by broken lines.

Fig. 2 is a schematic elevational representation of the overhead guard.

Fig. 3 is a schematic frontal representation of an industrial lift truck with the attached overhead guard assembly.

Fig. 4 is a schematic representation of a hydraulic piping system for vertically moving a hydraulic overhead guard assembly.

Referring to the drawings, wherein like reference numerals designate like parts, the reference numeral 8 designates an industrial lift truck, which as shown in Figs. 1 and 3, has a self-contained motive power unit 10, a seat power unit 10 of the lift truck 8. The guard assembly 18 is vertically slidably mounted on the vertical shafts 30 through sleeve bearings 28.

Each of the tubular members 19, 19' has welded thereto a reinforcing truss member 33. A cross member 36 of the guard 18 extends between and is connectedto the truss members 33. A hydraulic piston-cylinder assembly 34 attached at one end to the cross member 36 and at its other end to a suitable bracket 38 secured to the mast 32, provides the means for elevating and lowering the guard 18 in a substantially vertical direction. The piston-cylinder assembly 34 is operated by hydraulic pressure obtained from the lifttruck main hydraulic system, as shown in Fig. 4. 1

The hydraulic system shown in Fig. 4 comprises a pump 58 driven by suitable connection (not shown) to the. motive power unit of the lift truck. The pump discharges fluid under pressure through a pipe connection 56 to a multi-control valve 40, having individual control means for regulating the flow of fluid pressure to piston cylinder assemblies for raising and lowering the lifting platform 17, and for the tilting means of the lifting platform and to the raising and lowering means 34 of the overhead guard 18.

The raising of the overhead guard 18 is effected by adjusting a lever 62 of the control valve 40 to discharge fluid under pressure through supply port 64 into a supply pipe 42 connected to the bottom of the piston-cylinder assembly 34. A pressure relief valve 44 is connected to supply pipe 42 and discharges into a pipe connection 46 leading into a sump tank 48.

The lowering of the overhead guard 18 is effected by adjusting lever 62 of the control valve 40 to discharge fluid through supply port 66 into a supply pipe 50 connected to the top of the hydraulic piston-cylinder assembly 34. A pressure relief valve 52 is provided in line 50 and vents into a connection 54 with the return line 46.

Pressure fluid returned to the sump tank 48 is supplied to the pump 58 by pipe connection 60.

Similarly fluid under'pressure can be supplied to a piston-cylinder assembly for raising the lifting platform by operating control lever 74 to discharge fluid from supply port 76 of multi-valve 40 or for lowering the platform by discharge of fluid from supply port 78. The conventional fork lift platform tilting device also employing a piston-cylinder assembly for tilting or retracting is actuated to a tilt position by operating lever 68 to discharge fluid under pressure from supply port 70 or retracted by fluid pressure discharged from supply port 72.

The adjustable overhead guard, of this invention is suitable for use on industrial lift trucks. It not only protects the operator from falling objects but also allows entrance and operation of the lift truck within a low overhead clearance area such as a van-type trailer without the necessity of removing the overhead guard, as it is vertically adjustable by hydraulic means.

Thus, injuries caused by falling objects due to the failure to replace the overhead guard upon leaving such low overhead clearance areas are now eliminated. Also, injuries incurred within such areas are now eliminated since the guard is hydraulically operated to give vertical adjustments enabling the operator to remain at all times safely at the controls of the lift truck.

It is also more economical in that no time is lost in removing and replacing the guard to enable operation of the lift truck in low overhead areas. Also adjustments in the height of the guard are made quickly and simply from the operators seat as the guard is operated hydraulically and not mechanically or manually.

Since it is apparent that various changes and modifications may be made in the above specified embodiments without departing from the nature and spirit thereof, this invention is not limited thereto except as set forth the appended claims.

What is claimed is:

1. An adjustable overhead guard for use on industrial lift trucks comprising a horizontal frame section extending over and beyond the lift truck seat having vertical legs positioned in front of said lift truck seat, each of said vertical legs being slidably mounted on vertical shafts afiixed to the front end of said truck spaced apart from and parallel to the mast on each side of the lift truck for vertically raising and lowering said frame section while positioned substantially horizontally with respect to the truck operators seat, and hydraulic means for vertically raising and lowering said guard on the fixed shafts.

2. An overhead guard as set forth in claim 1 wherein the hydraulic means is controlled by a multicontrol valve having individual and separately operable controls for raising and lowering the platform, for tilting the platform and for raising and lowering the guard.

3. In combination with a fork lift truck having a hydraulically actuated lifting platform and means for tilting said platform, an overhead guard horizontally positioned over the operators seat, and slidably mounted on a pair of parallel vertical shafts afiixed to the front end of said truck and adjacent to the masts on which the lifting platform is supported for vertically raising and lowering said frame section while positioned substantially horizontally with respect to the truck operators seat, hydraulically operated means for vertically raising and lowering said overhead guard, and a common means for supplying fluid under pressure to actuate the platform and to raise and lower the overhead guard.

4. In combination with a fork lift truck having a hydraulically actuated lifting platform and means for tilting said platform, an overhead guard horizontally positioned over the operators seat and slidably mounted on a pair of parallel vertical shafts afiixed to the front end of said truck and adjacent to the masts on which the lifting platform is supported for vertically raising and lowering said frame section while positioned substantially horizontally with respect to the truck operators seat, hydraulically operated means for vertically raising and lowering said overhead guard, a common means for supplying fluid under pressure to activate the platform and to raise and lower the overhead guard, and control means interposed between said fluid supply means and the platform and the guard, said control means having separate and individual valves whereby the supply of fluid under pressure to the platform is controlled independently of the fluid supplied to the overhead guard.

5. In combination with a fork lift truck, a vertically adjustable overhead safety guard for the lift truck operator, said guard comprising a horizontal frame section extending over the operator and slidably mounted on vertical shafts aflixed to the truck for vertically raising and lowering said frame section while positioned substantially horizontally with respect to the truck operators seat, and hydraulic means for vertically raising and lowering said frame section.

References Cited in the file of this patent UNITED STATES PATENTS 2,351,679 Harris June 20, 1944 2,506,242 Shoemaker May 2, 1950 2,706,993 Forrest Apr. 26, 1955 2,754,019 Watson July 10, 1956 2,806,618 Cook Sept. 17, 1957 

